(1) Field of the Invention
This invention relates to a stereoscopic image display system that directs images with binocular parallax (i.e., an image for right eye and an image for left eye) separately at left and right eyes of an experiencing person to allow the experiencing person to visually recognize the images as a stereoscopic image without using special glasses.
(2) Description of the Related Art
As stereoscopic image display systems of this type, conventionally, there have been known those using a retroreflective screen (e.g., refer to JP 2006-113476 A (paragraphs 0014 to 0059, FIGS. 1 to 7)). With reference to FIG. 1 and FIG. 2, hereinafter, description will be given of a conventional stereoscopic image display system. FIG. 1 is a side view used for description of a principle of a display apparatus using a retroreflective screen. FIG. 2 is a plan view showing a schematic configuration of a conventional stereoscopic image display system.
In the display apparatus using the retroreflective screen, as shown in FIG. 1, the retroreflective screen 21 is disposed in a standing state on a line of sight of an experiencing person M. Moreover, a half mirror 22 is provided between the experiencing person M and the retroreflective screen 21. The half mirror 22 has a plane of incidence facing a facial surface of the experiencing person M. Further, a projector 23 is provided for emitting an image light beam L1 at a predetermined angle of view to the half mirror 22. The angle of view of the image light beam L1 emitted from the projector 23 and an angle of incidence of the image light beam L1 relative to the half mirror 22 are set appropriately, so that a field of view of the experiencing person M who sees the retroreflective screen 21 through the half mirror 22 in an image experience region is superimposed on an image light beam L2 obtained when the image light beam L1 reflected from the half mirror 22 is projected onto the retroreflective screen 21. Since the retroreflective screen 21 has a characteristic of reflecting the image light beam L2 in a direction of incidence of the image light beam L2, the image light beam L2 projected on the retroreflective screen 21 is reflected in the direction of incidence thereof, passes through the half mirror 22 and enters eyes of the experiencing person M. Thus, the experiencing person M can visually recognize the image light beam L2.
The conventional stereoscopic image display system is configured by use of the mechanism of display described above. Hereinafter, reference is made to FIG. 2. This stereoscopic image display system includes a projector 23R that emits an image light beam L1R for right eye, a projector 23L that emits an image light beam L1L for left eye, two half mirrors 22A and 22B, and the like. The image light beam L1R for right eye is emitted from the projector 23R, is reflected from the half mirrors 22A and 23B in this order, and is projected onto the retroreflective screen 21. The projected image light beam L2R is reflected in a direction of incidence thereof, passes through the half mirrors 22A and 22B, and enters the right eye of the experiencing person M. On the other hand, the image light beam L1L for left eye is emitted from the projector 23L, passes through the half mirror 22A, is reflected from the half mirror 22B, and is projected onto the retroreflective screen 21. The projected image light beam L2L is reflected in a direction of incidence thereof, passes through the half mirrors 22A and 22B, and enters the left eye of the experiencing person M. Since the image light beams L2R and L2L form parallax images, the experiencing person M can visually recognize a stereoscopic image.
However, the conventional stereoscopic image display system having the configuration described above has the following problem. That is, although the stereoscopic image display system allows an experiencing person to visually recognize a stereoscopic image by his/her naked eyes, with a relatively simple configuration, only a specific experiencing person (only one experiencing person) can visually recognize a stereoscopic image, but a plurality of experiencing persons can not visually recognize stereoscopic images at one time.